It applies to the overload and short-circuit protection, cable distribution, power load parameter monitoring with three-phase and single phase, rated voltage of lower than 0.4KV, rated insulation voltage of 0.66KV and frequency of 50HZ (maximum capacity of three-phase is 400KVA and single phase is 50KVA), and it is an outdoor variable low voltage distribution box which is accessible to the public (hereinafter is referred to as distribution box).